Communication method and apparatus

This is a continuation of International Patent Application No. PCT/CN2020/110627, filed on Aug. 21, 2020, which claims priority to Chinese Patent Application No. 201910888796.1, filed on Sep. 19, 2019, and Chinese Patent Application No. 202010550068.2, filed on Jun. 16, 2020. All of the aforementioned patent applications are hereby incorporated by reference in their entireties.

This application relates to the field of communication technologies, and in particular, to a communication method and apparatus.

For a terminal that can access a 4th generation (4G) network and a 5th generation (5G) network, how to ensure that a service of the terminal is not affected when the terminal is moved between the 4G network and the 5G network, to improve overall communication efficiency of the network is a problem that urgently needs to be resolved.

Embodiments of this application provide a communication method and apparatus, to improve overall communication efficiency of a network.

To achieve the foregoing objective, this application provides the following technical solutions.

According to a first aspect, a communication method is provided. The method includes: A first mobility management network element in a first network obtains information about N intermediate session management network elements that are capable of serving a terminal in the first network. If the N intermediate session management network elements include a combined intermediate session management network element, the first mobility management network element determines that the combined intermediate session management network element is a first intermediate session management network element corresponding to a first session of the terminal in the first network, and N is an integer greater than 0. The combined intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in a second network. The first network may be a 5G network. In this case, the second network may be a 4G network. Alternatively, the first network may be a 4G network. In this case, the second network may be a 5G network. According to the method provided in the first aspect, when selecting an intermediate session management network element, the first mobility management network element preferentially selects the combined intermediate session management network element for the terminal, to improve overall communication efficiency of the network. For example, network address resources are reduced to simplify network planning and deployment complexity, a quantity of nodes in the network is reduced to simplify network operation and maintenance workload, and signaling between the nodes in the network is reduced to reduce network service load.

In a possible implementation, the first network is the 5G network and the second network is the 4G network, and the method is applied to the following scenario: The first session is the 1session established by the terminal on the first mobility management network element; or an intermediate session management network element corresponding to a session that has been established by the terminal on the first mobility management network element is not the combined intermediate session management network element.

In a possible implementation, the first network is the 5G network and the second network is a 4G network; and that the first mobility management network element determines that the combined intermediate session management network element is a first intermediate session management network element corresponding to a first session of the terminal in the first network includes: When an intermediate session management network element corresponding to at least one session that has been established by the terminal on the first mobility management network element is the combined intermediate session management network element, the first mobility management network element determines that the combined intermediate session management network element is the first intermediate session management network element corresponding to the first session. In this possible implementation, the combined intermediate session management network element does not need to re-establish the session, but only needs to update the session. This can avoid a waste of resources.

In a possible implementation, the first network is the 4G network and the second network is the 5G network, and the method is applied to the following scenario: The first session is the 1session established by the terminal on the first mobility management network element.

In a possible implementation, an intermediate session management network element that is in the information about the N intermediate session management network elements and that includes indication information is the combined intermediate session management network element, and the method further includes: The first mobility management network element determines the combined intermediate session management network element based on the indication information.

In a possible implementation, the indication information is a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as an intermediate session management network element in the 4G network.

In a possible implementation, the combined intermediate session management network element further combines an anchor session management network element in the 4G network, and the indication information is a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network.

According to a second aspect, a communication method is provided. The method includes: When a terminal needs to be migrated from a source network to a target network, a second mobility management network element in a first network obtains information about N intermediate session management network elements corresponding to a session of the terminal in the source network, and determines, based on types of the N intermediate session management network elements, a second intermediate session management network element corresponding to a session of the terminal in the target network. The information about the N intermediate session management network elements is used to indicate a type of each of the N intermediate session management network elements, the type includes an independent intermediate session management network element or a combined intermediate session management network element, the combined intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in a second network, the independent intermediate session management network element is capable of providing session management only in either one of the first network and the second network; the source network is the first network and the target network is the second network, or the source network is the second network and the target network is the first network; and N is an integer greater than 0. The first network may be a 5G network and the second network may be a 4G network. According to the method provided in the second aspect, when the terminal needs to be migrated from the source network to the target network, the intermediate session management network element corresponding to the session of the terminal in the target network may be determined depending on whether the intermediate session management network element is the combined intermediate session management network element. If the combined intermediate session management network element needs to be determined for the session of the terminal in the target network, the combined intermediate session management network element may be preferentially determined for the session of the terminal in the target network, such that the session of the terminal is anchored to the combined intermediate session management network element after the network migration. Therefore, overall communication efficiency of the network is improved. For example, network address resources are reduced to simplify network planning and deployment complexity, a quantity of nodes in the network is reduced to simplify network operation and maintenance workload, and signaling between the nodes in the network is reduced to reduce network service load.

In a possible implementation, the source network is the first network, the first network is the 5G network, the target network is the second network, and the second network is the 4G network; and that the second mobility management network element determines, based on types of the N intermediate session management network elements, a second intermediate session management network element corresponding to a session of the terminal in the target network includes: If the N intermediate session management network elements include the combined intermediate session management network element, the second mobility management network element selects the combined intermediate session management network element in the N intermediate session management network elements as the second intermediate session management network element corresponding to the session of the terminal in the second network.

In a possible implementation, the method further includes: The second mobility management network element sends a relocation request to a third mobility management network element in the second network, where the relocation request includes information about the second intermediate session management network element and indication information, and the indication information is used to indicate that the second intermediate session management network element is the combined intermediate session management network element.

In a possible implementation, the indication information is a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as an intermediate session management network element in the 4G network.

In a possible implementation, the combined intermediate session management network element further combines an anchor session management network element in the 4G network, the indication information is a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as an intermediate session management network element in the 4G network, and the node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the intermediate session management network element in the 4G network is associated with a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network.

The node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the intermediate session management network element in the 4G network may be derived by an access and mobility function (AMF) based on the node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network, or may be derived by the combined intermediate session management network element based on the node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network.

In a possible implementation, the source network is the second network, the second network is the 4G network, the target network is the first network, the first network is the 5G network, and N=1. The method further includes: The second mobility management network element obtains information about M intermediate session management network elements that are capable of serving the terminal in the first network, where the information about the M intermediate session management network elements is used to indicate a type of each of the M intermediate session management network elements. That the second mobility management network element determines, based on types of the N intermediate session management network elements, a second intermediate session management network element corresponding to a session of the terminal in the target network includes: The second mobility management network element determines, based on the types of the N intermediate session management network elements and the types of the M intermediate session management network elements, the second intermediate session management network element corresponding to a second session of the terminal in the first network.

In a possible implementation, that the second mobility management network element determines, based on the types of the N intermediate session management network elements and the types of the M intermediate session management network elements, the second intermediate session management network element corresponding to a second session of the terminal in the first network includes: If the N intermediate session management network elements include the combined intermediate session management network element, and the combined intermediate session management network element belongs to the M intermediate session management network elements, the second mobility management network element preferentially selects, from the M intermediate session management network elements, the combined intermediate session management network element as the second intermediate session management network element corresponding to the second session; or if the N intermediate session management network elements do not include the combined intermediate session management network element, or the N intermediate session management network elements include the combined intermediate session management network element but the combined intermediate session management network element does not belong to the M intermediate session management network elements, the second mobility management network element preferentially selects, from the M intermediate session management network elements, a combined intermediate session management network element as the second intermediate session management network element corresponding to the second session. If the N intermediate session management network elements include the combined intermediate session management network element, and the combined intermediate session management network element belongs to the M intermediate session management network elements, the combined intermediate session management network element selected using this possible implementation does not need to re-establish the session, but only needs to update the session. This can avoid a waste of resources.

In a possible implementation, the method further includes: The second mobility management network element sends a request message to the combined intermediate session management network element, where the request message is used to request the combined intermediate session management network element to update the corresponding session, and the request message includes a session identifier allocated by the combined intermediate session management network element to the terminal in the second network.

According to a third aspect, a communication method is provided. The method includes: A third mobility management network element in a second network receives a relocation request from a second mobility management network element in a first network, where the relocation request includes information about a second intermediate session management network element and indication information, the second intermediate session management network element is an intermediate session management network element that is determined by the second mobility management network element for a terminal and that corresponds to a session of the terminal in the second network, the indication information is used to indicate that the second intermediate session management network element is a combined intermediate session management network element, and the combined intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in the second network; the third mobility management network element obtains information about M intermediate session management network elements that are capable of serving the terminal in the second network; and the third mobility management network element determines, based on the relocation request and the M intermediate session management network elements, that one combined intermediate session management network element is the intermediate session management network element corresponding to the session of the terminal in the second network. The first network may be a 5G network and the second network may be a 4G network. According to the method provided in the third aspect, when the terminal needs to be migrated from the 5G network to the 4G network, the combined intermediate session management network element may be preferentially determined for the session of the terminal in the 4G network, such that the session of the terminal is anchored to the combined intermediate session management network element after the network migration. Therefore, overall communication efficiency of the network is improved. For example, network address resources are reduced to simplify network planning and deployment complexity, a quantity of nodes in the network is reduced to simplify network operation and maintenance workload, and signaling between the nodes in the network is reduced to reduce network service load.

In a possible implementation, the indication information is a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as an intermediate session management network element in the 4G network.

In a possible implementation, the combined intermediate session management network element further combines an anchor session management network element in the 4G network, the indication information is a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as an intermediate session management network element in the 4G network, and the node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the intermediate session management network element in the 4G network is associated with a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network.

The node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the intermediate session management network element in the 4G network may be derived by an AMF based on the node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network, or may be derived by the combined intermediate session management network element based on the node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network.

In a possible implementation, the method further includes: If the second intermediate session management network element belongs to the M intermediate session management network elements, the third mobility management network element determines that the second intermediate session management network element is the intermediate session management network element corresponding to the session of the terminal in the second network; or if the second intermediate session management network element does not belong to the M intermediate session management network elements, the third mobility management network element determines that one combined intermediate session management network element in the M intermediate session management network elements is the intermediate session management network element corresponding to the session of the terminal in the second network. If the second intermediate session management network element belongs to the M intermediate session management network elements, the combined intermediate session management network element selected using this possible implementation does not need to re-establish the session, but only needs to update the session. This can avoid a waste of resources.

According to a fourth aspect, a communication method is provided. The method includes: When a terminal needs to be migrated from a first network to a second network, a fourth mobility management network element in the second network obtains information about N intermediate session management network elements that are capable of serving the terminal in the second network; the fourth mobility management network element obtains, from a subscriber data management network element, information about M intermediate session management network elements that serve the terminal in the first network; and if a session created by the terminal on the fourth mobility management network element is the 1session, the fourth mobility management network element determines, based on types of the N intermediate session management network elements and the M intermediate session management network elements, an intermediate session management network element corresponding to the 1session, where the types include an independent intermediate session management network element and a combined intermediate session management network element, the combined intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in the second network, and the independent intermediate session management network element is capable of providing session management only in either one of the first network and the second network. The first network may be a 5G network. In this case, the second network may be a 4G network. Alternatively, the first network may be a 4G network. In this case, the second network may be a 5G network. According to the method provided in the fourth aspect, when the terminal needs to be migrated from the first network to the second network, the combined intermediate session management network element may be preferentially determined for the session of the terminal in the second network, such that the session of the terminal is anchored to the combined intermediate session management network element after the network migration. Therefore, overall communication efficiency of the network is improved. For example, network address resources are reduced to simplify network planning and deployment complexity, a quantity of nodes in the network is reduced to simplify network operation and maintenance workload, and signaling between the nodes in the network is reduced to reduce network service load.

In a possible implementation, that the fourth mobility management network element determines, based on types of the N intermediate session management network elements and the M intermediate session management network elements, an intermediate session management network element corresponding to the 1session includes: If there is a combined intermediate session management network element belonging to both the M intermediate session management network elements and the N intermediate session management network elements, the fourth mobility management network element selects the combined intermediate session management network element belonging to both the M intermediate session management network elements and the N intermediate session management network elements as the intermediate session management network element corresponding to the 1session; or if the M intermediate session management network elements do not include the combined intermediate session management network element, or the M intermediate session management network elements include the combined intermediate session management network element but the combined intermediate session management network element in the M intermediate session management network elements does not belong to the N intermediate session management network elements, the fourth mobility management network element preferentially selects a combined intermediate session management network element in the N intermediate session management network elements as the intermediate session management network element corresponding to the 1session. If the combined intermediate session management network element belongs to both the M intermediate session management network elements and the N intermediate session management network elements, the combined intermediate session management network element selected using this possible implementation does not need to re-establish the session, but only needs to update the session. This can avoid a waste of resources.

In a possible implementation, the first network is the 4G network and the second network is the 5G network, and the method further includes: If the session created by the terminal on the fourth mobility management network element is not the 1session, the fourth mobility management network element preferentially selects a combined intermediate session management network element in an intermediate session management network element corresponding to a session that has been established by the terminal on the fourth mobility management network element as an intermediate session management network element corresponding to the created session.

According to a fifth aspect, a communication method is provided. The method includes: A network discovery network element in a first network receives a registration request from an intermediate session management network element in the first network, where the registration request includes information about the intermediate session management network element, the information about the intermediate session management network element includes indication information, the indication information is used to indicate that the intermediate session management network element is a combined intermediate session management network element, and the combined intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in a second network; and the network discovery network element sends a registration response to the intermediate session management network element. The first network may be a 5G network and the second network may be a 4G network. According to the method provided in the fifth aspect, the combined intermediate session management network element may register with the network discovery network element, and the network discovery network element may determine, using the carried indication information, which intermediate session management network elements are combined intermediate session management network elements and which intermediate session management network elements are independent intermediate session management network elements, to support a subsequent process such as intermediate session management network element selection.

In a possible implementation, the indication information is a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as an intermediate session management network element in the 4G network.

In a possible implementation, the combined intermediate session management network element further combines an anchor session management network element in the 4G network, the indication information is a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as an intermediate session management network element in the 4G network, and the node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the intermediate session management network element in the 4G network is associated with a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network.

The node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the intermediate session management network element in the 4G network may be derived by an AMF based on the node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network, or may be derived by the combined intermediate session management network element based on the node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network.

According to a sixth aspect, a communication method is provided. The method includes: An intermediate session management network element in a first network sends a registration request to a network discovery network element in the first network, where the registration request includes information about the intermediate session management network element, the information about the intermediate session management network element includes indication information, the indication information is used to indicate that the intermediate session management network element is a combined intermediate session management network element, and the combined intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in a second network; and the intermediate session management network element receives a registration response from the network discovery network element. The first network may be a 5G network and the second network may be a 4G network. According to the method provided in the sixth aspect, the combined intermediate session management network element may register with the network discovery network element, and the network discovery network element may determine, using the carried indication information, which intermediate session management network elements are combined intermediate session management network elements and which intermediate session management network elements are independent intermediate session management network elements, to support a subsequent process such as intermediate session management network element selection.

In a possible implementation, the indication information is a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as an intermediate session management network element in the 4G network.

In a possible implementation, the combined intermediate session management network element further combines an anchor session management network element in the 4G network, the indication information is a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as an intermediate session management network element in the 4G network, and the node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the intermediate session management network element in the 4G network is associated with a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network.

The node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the intermediate session management network element in the 4G network may be derived by an AMF based on the node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network, or may be derived by the combined intermediate session management network element based on the node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network.

According to a seventh aspect, a communication method is provided. The method includes: A subscriber data management network element receives a registration request from a combined intermediate session management network element, where the registration request includes an identifier of an intermediate session management network element that is in a second network and that corresponds to a session managed by the combined intermediate session management network element in a first network, and the combined intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in the second network; and the subscriber data management network element sends a registration response to the combined intermediate session management network element. According to the method provided in the seventh aspect, when no N26 interface exists between an AMF and a mobility management entity (MME), the subscriber data management network element may obtain the identifier of the intermediate session management network element that is in the second network and that corresponds to the session managed by the combined intermediate session management network element in the first network. As such, the identifier of the intermediate session management network element that is in the second network and that corresponds to the session is sent to a mobility management network element in the second network as required by the mobility management network element in the second network.

In a possible implementation, the identifier of the intermediate session management network element that is in the second network and that corresponds to the session managed by the combined intermediate session management network element in the first network is derived using a node name that is of an anchor session management network element in the second network and that corresponds to the session managed by the combined intermediate session management network element in the first network.

According to an eighth aspect, a communication method is provided. The method includes: A combined intermediate session management network element sends a registration request to a subscriber data management network element, where the registration request includes an identifier of an intermediate session management network element that is in a second network and that corresponds to a session managed by the combined intermediate session management network element in a first network, and the combined intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in the second network; and the combined intermediate session management network element receives a registration response from the subscriber data management network element. According to the method provided in the eighth aspect, when no N26 interface exists between an AMF and an MME, the subscriber data management network element may obtain the identifier of the intermediate session management network element that is in the second network and that corresponds to the session managed by the combined intermediate session management network element in the first network, such that the identifier of the intermediate session management network element that is in the second network and that corresponds to the session is sent to a mobility management network element in the second network as required.

In a possible implementation, the identifier of the intermediate session management network element that is in the second network and that corresponds to the session managed by the combined intermediate session management network element in the first network is derived using a node name that is of an anchor session management network element in the second network and that corresponds to the session managed by the combined intermediate session management network element in the first network.

According to a ninth aspect, a communication apparatus is provided. The apparatus is located in a first network and includes: an obtaining unit configured to obtain information about N intermediate session management network elements that are capable of serving a terminal in a first network, where the N intermediate session management network elements include a combined intermediate session management network element, the combined intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in a second network, and N is an integer greater than 0; and a determining unit configured to determine that the combined intermediate session management network element is a first intermediate session management network element corresponding to a first session of the terminal in the first network.

In a possible implementation, the first network is a 5G network, the second network is a 4G network, and the first session is the 1session established by the terminal on the apparatus; or an intermediate session management network element corresponding to a session that has been established by the terminal on the apparatus is not the combined intermediate session management network element.

In a possible implementation, the first network is a 5G network and the second network is a 4G network; and the determining unit is configured to: when an intermediate session management network element corresponding to at least one session that has been established by the terminal on the apparatus is the combined intermediate session management network element, determine that the combined intermediate session management network element is the first intermediate session management network element corresponding to the first session.

In a possible implementation, the first network is a 4G network and the second network is a 5G network, and the first session is the 1session established by the terminal on the apparatus.

In a possible implementation, an intermediate session management network element that is in the information about the N intermediate session management network elements and that includes indication information is the combined intermediate session management network element, and the determining unit is further configured to determine the combined intermediate session management network element based on the indication information.

In a possible implementation, the indication information is a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as an intermediate session management network element in the 4G network.

In a possible implementation, the combined intermediate session management network element further combines an anchor session management network element in the 4G network, and the indication information is a node name of the combined intermediate session management network element when the combined intermediate session management network element serves as the anchor session management network element in the 4G network.

According to a tenth aspect, a communication apparatus is provided. The apparatus is located in a first network and includes: an obtaining unit configured to: when a terminal needs to be migrated from a source network to a target network, obtain information about N intermediate session management network elements corresponding to a session of the terminal in the source network, where the information about the N intermediate session management network elements is used to indicate a type of each of the N intermediate session management network elements, the type includes an independent intermediate session management network element or a combined intermediate session management network element, the combined intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in a second network, the independent intermediate session management network element is capable of providing session management only in either one of the first network and the second network; the source network is the first network and the target network is the second network, or the source network is the second network and the target network is the first network; and N is an integer greater than 0; and a determining unit configured to determine, based on the types of the N intermediate session management network elements, a second intermediate session management network element corresponding to a session of the terminal in the target network.

In a possible implementation, the source network is the first network, the first network is a 5G network, the target network is the second network, and the second network is a 4G network; and the determining unit is configured to: if the N intermediate session management network elements include the combined intermediate session management network element, select the combined intermediate session management network element in the N intermediate session management network elements as the second intermediate session management network element corresponding to the session of the terminal in the second network.